Chevrolet 12578036 Valve,EGR

Exhaust Gas Recirculation (EGR) cuts the NOx emissions by minimizing the combustion temperatures mainly with the help of EGA valve which helps in recycling the exhaust gasses into the combustion chamber. This type of valve is usually open during normal warm engine running and at above idle speed and the flow of gas is regulated with help of differences in vacuum and exhaust back pressure. There are three types of EGA valves: DEFINITIONS: Digital, Negative Backpressure, and Integrated Electronic. The Digital EGA valve correctly regulates exhaust gas delivery to the engine using a membrane controlled by a solenoid; the exhaust gas flow is regulated through incrementally-sized orifices. EGA valve with Negative Back Pressure is controlled with a diaphragm, which opens under the vacuum set by the engine while Integrated Electronic EGA valve has vacuum regulator and position sensor working in one housing and receives the variable current from the ECM to control the flow of exhaust gases with reference to the information obtained from the other sensors. To diagnose the Negative Backpressure EGR valve, one can check for play, look into changes in RPM when ever the push the diaphragm and check vacuum signals. In the Integrated Electronic EGR valve tests include applying vacuum and then observing its travel under various ignition status. It should be mentioned that the mentioned Digital EGR valve may be identified with the help of a special scan tool only. For the component replacement of the EGA valve, the vacuum hose or the electrical connection of the valve is removed; it is then detached from the intake manifold carefully, and cleaned of all deposits that have accumulated on it before the fresh valve, complete with a new gasket, is installed, with all surfaces having to be free of the old materials.

The EGA valve is found on the intake manifold and in most cases, a problem in the emissions system results from a stuck or corroded EGA valve. Feel underneath the valve and push on the diaphragm to confirm its status with the engine cold to keep yourself from getting burnt. The membrane should be maneuverable using moderate pressure. In case it does not move at all or moves with great difficulty, change the EGA valve to a new one. Whenever you are uncertain about its condition, compare this free movement with that of a new valve.

Passages cast in intake manifold allow the EGR system to meter exhaust gases into the engine induction system. This is achieved by a valve that operates under vacuum or back pressure control in response to the engine load. Rough idling or stalling at idle, rough engine performance during light throttle application, and stalling during deceleration are some of the problems related to EGR systems in engines. Start the vehicle's engine then manually raise its EGR diaphragm to inspect through it. If the engine shuts off or its idle speed drops significantly, then the EGR valve is working properly. Examine all hoses connected to the valve for breaks, leaks, and kinks. Detach vacuum hose from the EGR valve and apply vacuum using a vacuum pump. The engine stumbling indicates that the vacuum diaphragm is working fine. Consult a reliable automotive repair company for proper checks on how effective your EGR control solenoid is operating on this vehicle. To replace any components, first separate the hose from the EGR valve before removing nuts or bolts that hold it onto either adapter or intake manifold. As you install another gasket lift out EGR valve from engine after it has been cleaned with dry cloth on mounting surfaces, put it in place with new EGR valve and proceed to connect hose for vacuum signal. Checking this linear EGR valve requires special electronic diagnostic equipment hence a qualified repair facility should do that examination. When replacing it, unplug electrical connector then take away mounting bolts followed by EGR valve which finally results in cleaning of mounting surface before installation of new gasket finished by tightening bolts firmly as well as connecting electrical connector into EGR valve itself.

The EGR valve in GM vehicles is found on the intake manifold near the carburetor. Faults in this system often stem from a stuck or corroded EGR valve. To check, with a cold engine, manually push the diaphragm under the EGR valve. It should move up and down with moderate pressure. If it doesn't, or requires excessive force, replace the valve. If unsure, compare your valve's movement with a new one at a parts store.

The system is designed to minimize the NOx gases that come out of the exhaust, which are caused by high sulphur content and the temperature of combustion. In order to lower peak temperature and NOx formation, some of the exhaust gas is returned to the combustion cycle; this is done again using the passages within the intake manifold although most of the routing elements are hidden. Maintenance is mainly concerned with checking the vacuum hoses and the EGR valve. The only part included in the check that is known to wear out is the thermal vacuum switch. During idle or deceleration the EGR System does not work and is controlled by the Thermal Vacuum Switch that comes to function when the engine is warmed up. Rough idling, stalling and poor acceleration on light throttle are some of the problems that may be associated with this system. To check the EGR valve physically, the valve is the one located near to the intake manifold, check for the flow of the diaphragm and also the response of the engine when the diaphragm of the valve is forcefully depressed. Check vacuum gets to the EGR valve and use vacuum gauge to test the thermal vacuum switch. If required, EGR can be removed by disconnecting the vacuum hose, unscrewing the nuts/bolts, cleaning mounting surface, and putting new valve with gasket. For the thermal vacuum switch, remove the drain coolant, remove or disconnect the hoses, then remove the switch; apply thread sealer when reinstalling the switch then tighten to the standard torque.

To check the EGR system, start the engine and manually lift the EGR diaphragm. If the engine stalls or the idle drops considerably, it indicates that the EGR valve is operating properly.

Special electronic diagnostic equipment is needed for checking the linear EGR valve system, and this should be performed by a qualified repair facility.

If you suspect an issue with the EGR system, check all hoses connected to the EGR valve for breaks, leaks, or kinks.